1 david hitlin frascati superb workshop march 17, 2006
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David Hitlin Frascati SuperB Workshop March 17, 2006 1
David Hitlin
Frascati SuperB WorkshopMarch 17, 2006
David Hitlin Frascati SuperB Workshop March 17, 2006 2
Reusing existing detectors at SuperB With luck, we will soon have to face the question of whether
SuperB should have a new detector built from scratch, or whether an existing detector (BABAR, Belle, or even CLEO-II) could be upgraded to do the job
In order to meaningfully discuss this question in detail, it is necessary to nail down a few important parameters Do we collide every bunch or collide trains kicked out of rings? The energy asymmetry (7x4, 8x3.5, 9x3.1) Two beams vs four beams
A four-beam machine can have boosted decays in both the “forward” and “backward” directions. This is a major perturbation on the design Requires a detector that has essentially the forward
section of BABAR or Belle in both the forward an backward directions A much longer solenoid and flux return is needed
David Hitlin Frascati SuperB Workshop March 17, 2006 3
By the end of the year, we may need to provide preliminary details on schedules, costs and R&D needs for both the collider and detector
In order to confront the detector side, it is helpful to have a specific configuration in mind An upgrade of either BABAR or Belle would, at first glance,
seem to be a perfectly adequate detector for 1036 at SuperB A first look at modifying BABAR, however, turns up issues
Using BABAR as the foundation seems feasible, however Using Belle would likely generate essentially a similar end
result (cf Tim Gershon’s talk) A first look turns up a variety constraints, many of which
are generic
We need to grapple with this question now
David Hitlin Frascati SuperB Workshop March 17, 2006 4
Collider scheme has a direct effect A linear collider-type machine and a storage ring-type
machine have very different time structures and currents These differences directly effect detector design Sensitivities
Beam pipe diameter and thickness (cooling?) Trigger/DAQ system - fundamental Response time of detector subsystems
Tracker Electromagnetic calorimeter
Radiation hardness
David Hitlin Frascati SuperB Workshop March 17, 2006 5
Linear collider vs storage ring Linear collider
Small diameter, uncooled beampipe “SLD” like DAQ CsI(Tl) OK, at least for the barrel Drift chamber tracker
Storage ring with LC final focus Cooled beampipe thicker material (two walls + water)
likely larger diameter SuperBABAR type DAQ Fast, radiation hard EMC (LSO/LYSO, pureCsI)
Barrel/endcap radiation sensitivity depends on luminosity term
Fast decay time is an advantage A drift chamber is marginal
A silicon tracker presents a multiple scattering problem
David Hitlin Frascati SuperB Workshop March 17, 2006 6
Backgrounds Naïve scaling by current indicates that the occupancy
and radiation damage issues at a conventional 1036 machine are much reduced at a linear collider type machine and are slightly better than SuperPEP-II or SuperKEKB in the new storage ring scheme, due to reduced circulating currents (scaling as the current, if the PEP-II luminosity term can be controlled)
Background sources Current-related Luminosity-related Beam-beam Touschek (intrabunch scattering) Synchrotron radiation
We must move beyond naïve scaling to a Decay Turtle type calculation of lost particle backgrounds
David Hitlin Frascati SuperB Workshop March 17, 2006 7
Detector elements – BABAR foundation
More conservative Less conservative
Retain Rebuild/Add Retain Rebuild/AddSolenoid SVT(Strips) Solenoid SVT(Pixels+strips)
Flux return Drift Chamber Flux return Drift Chamber
Barrel EMC Endcap EMC(s) Barrel EMC
LST’s DIRC SOB Endcap EMC(s)
Trigger/DAQ Barrel PID
Forward PID
IFR (especially EC)
Trigger/DAQ
A constant of the motion: remove the Support Tube
David Hitlin Frascati SuperB Workshop March 17, 2006 8
SuperB BABAR strawman – I
M A G N E T
C A B L E S
CL
C
Q 5Q 2
C Y L I N D R I C A L R E S I S T I V EP L A T E C H A M B E R
D .C .E L E C T .
Q 4Q 2
Q 5
1 1 4 9
D R I F TC H A M B E R
C A B L E S
5 0
F L O O R
1 6 5 5
3 7 0
E N D D O O R F L U X R E T U R NP L A T E S E G M E N T AT I O N
( 9 ) 2 0 M M T H K P L A T E S
( 4 ) 3 0 M M T H K P L A T E S
( 4 ) 5 0 M M T H K P L A T E S
( 1 ) 1 0 0 M M T H K P L A T E
+
-
R E S I S T I V E P L A T E C H A M B E R S I N G A P S( 1 9 ) P L A N E S I N B A R R E L
( 1 8 ) P L A N E S I N E N D D O O R S
C U R TA I N W A L L
S U P E R C O N D U C T I N G S O L E N O I D
F L U X
R E T U R N
Q 4
F O R W A R D E N D P L U G
C O U N T E R W E I G H T1 5 5 5
3 0 0 0
-
+
B A R R E L F L U X R E T U R N
P L A T E S E G M E N T AT I O N
( 9 ) 2 0 M M T H K P L A T E S( 4 ) 3 0 M M T H K P L A T E S
( 3 ) 5 0 M M T H K P L A T E S ( 2 ) 1 0 0 M M T H K P L AT E S
3 2 0 9
3 5 0 0
D IR CE L E C T .
1 5 0
2 3 9 5
1 7 .2 0
2 2 9 5
4 5 6 6
3 2 0 9
e
e
e
e
4 5 0 0
3 1 5 0
1 1 4 9
D E W A R
S V T
B A R R E L C A L O R IM E T E R
5 5 0 0
H O R S E C O L L A RA S S E M B LY
1 3 8 4
F
F
C
C
A
A
L
L
F
B
David Hitlin Frascati SuperB Workshop March 17, 2006 9
Detector protractor – 9 on 3.1 GeV ’s
lab9 G eV on 3.109 G eV
60 o60 o
80 o80 o
70 o70 o
50 o50 o
40 o40 o
30 o30 o
20 o20 o
10 o10 o
0 o0 o
90 o
c o s c m
.7.5
.5
.2
.2
0
.4
.4
.1.1
.6
.6
.3
.3
.7.8
.8
.9
.85
.92.94
.96
.98
.99 .9.85
.92.94 .96.98
(4 ) =0.56S
BACKWARDPOLAR ANGLES
FORWARDPOLAR ANGLES
David Hitlin Frascati SuperB Workshop March 17, 2006 10
Detector protractor – 8 on 3.5 GeV ’s
David Hitlin Frascati SuperB Workshop March 17, 2006 11
Detector protractor – 7 on 4 GeV ’s
David Hitlin Frascati SuperB Workshop March 17, 2006 12
SuperB BABAR strawman – I
M A G N E T
C A B L E S
CL
C
Q 5Q 2
C Y L I N D R I C A L R E S I S T I V EP L A T E C H A M B E R
D .C .E L E C T .
Q 4Q 2
Q 5
1 1 4 9
D R I F TC H A M B E R
C A B L E S
5 0
F L O O R
1 6 5 5
3 7 0
E N D D O O R F L U X R E T U R NP L A T E S E G M E N T AT I O N
( 9 ) 2 0 M M T H K P L A T E S
( 4 ) 3 0 M M T H K P L A T E S
( 4 ) 5 0 M M T H K P L A T E S
( 1 ) 1 0 0 M M T H K P L A T E
+
-
R E S I S T I V E P L A T E C H A M B E R S I N G A P S( 1 9 ) P L A N E S I N B A R R E L
( 1 8 ) P L A N E S I N E N D D O O R S
C U R TA I N W A L L
S U P E R C O N D U C T I N G S O L E N O I D
F L U X
R E T U R N
Q 4
F O R W A R D E N D P L U G
C O U N T E R W E I G H T1 5 5 5
3 0 0 0
-
+
B A R R E L F L U X R E T U R N
P L A T E S E G M E N T AT I O N
( 9 ) 2 0 M M T H K P L A T E S( 4 ) 3 0 M M T H K P L A T E S
( 3 ) 5 0 M M T H K P L A T E S ( 2 ) 1 0 0 M M T H K P L AT E S
3 2 0 9
3 5 0 0
D IR CE L E C T .
1 5 0
2 3 9 5
1 7 .2 0
2 2 9 5
4 5 6 6
3 2 0 9
e
e
e
e
4 5 0 0
3 1 5 0
1 1 4 9
D E W A R
S V T
B A R R E L C A L O R IM E T E R
5 5 0 0
H O R S E C O L L A RA S S E M B LY
1 3 8 4
F
F
C
C
A
A
L
L
F
B
lab9 G eV on 3.109 G eV
60 o60 o
80 o80 o
70 o70 o
50 o50 o
40 o40 o
30 o30 o
20 o20 o
10 o10 o
0 o0 o
90 o
c o s c m
.7.5
.5
.2
.2
0
.4
.4
.1.1
.6
.6
.3
.3
.7.8
.8
.9
.85
.92.94
.96
.98
.99 .9.85
.92.94 .96.98
(4 ) =0.56S
David Hitlin Frascati SuperB Workshop March 17, 2006 13
SuperB BABAR strawman – I
lab9 G eV on 3.109 G eV
60 o60 o
80 o80 o
70 o70 o
50 o50 o
40 o40 o
30 o30 o
20 o20 o
10 o10 o
0 o0 o
90 o
c o s c m
.7.5
.5
.2
.2
0
.4
.4
.1.1
.6
.6
.3
.3
.7.8
.8
.9
.85
.92.94
.96
.98
.99 .9.85
.92.94 .96.98
(4 ) =0.56S
David Hitlin Frascati SuperB Workshop March 17, 2006 14
Support tube
The support tube has some construction/alignment advantages, but the resolution penalty due to multiple scattering is severe It should be done away with in an upgrade Mount pixels/SVT on the beam pipe or on main tracker
David Hitlin Frascati SuperB Workshop March 17, 2006 15
Vertexing The SVT we have been discussing, originally based on the
SuperBABAR concept, involves two initial pixel layers followed by a ~5 layer SVT, starting at a very small radius (≤1 cm) This has sufficiently good primary vertex resolution to allow an
energy asymmetry as small as 7x4 GeV if the beam pipe radius is ≤10mm
In the storage ring-based design, things may be different With currents of 1-2 A, water cooling required A cooled beam pipe would have more material and would
require a larger radius for the first tracking layer What is the minimum practical beam pipe radius?
Needs a preliminary IP design and simulation
David Hitlin Frascati SuperB Workshop March 17, 2006 16
Main Tracking In a linear collider, a drift chamber (even a jet chamber)
would be the clear choice In the storage ring design, the viability of a gas-based solution
remains to be demonstrated Drift Chamber
Carbon fiber mechanics would be advantageous for the endplates, especially if we want to deploy endcap PID
Where do we mount the on-chamber electronics? In BABAR, the drift chamber electronics is entirely in the
backward direction Can tracking solid angle be extended below ~300 mrad?
Silicon Tracker Requires a large area of silicon (CMS=200 m2) Must perforce be double-sided, with Si thickess < 200m Even so, mass resolution is worse than for a gas-based tracker
Choice requires a detailed understanding of backgrounds
David Hitlin Frascati SuperB Workshop March 17, 2006 17
EMC Should the barrel CsI(Tl) calorimeter be retained?
There is already some radiation damage observed (barrel & EC) The mechanical structure of the existing EMC barrel is a major
constraint Projective towers, displacement of collision point
Calorimeter would have to be completely disassembled for shipping
Several of the important new physics objectives (most are related to recoil-related studies) make hermeticity increasingly important
This motivates the addition of a backward EMC endcap Both a forward and backward EMC endcap should be fast and
radiation-hard (LSO/LYSO), as should the barrel, if it is replaced
Smaller Molière radius and radiation length and fast decay time are a significant advantage
David Hitlin Frascati SuperB Workshop March 17, 2006 18
EMC Projectivity & mechanics EMC crystals are projective in , very nearly in The projective geometry itself is independent of boost The offset of the IP, meant to optimize solid angle
coverage for a given boost, is a non-negliglible constraint on other boosts
If the EMC mechanics were to be rebuilt: By removing crystals from the forward barrel and adding new
crystals at the rear, one could optimize for a lower boost By stiffening the carbon fiber egg crate structures with an
inner carbon fiber wall, one could reduce the dead material between crystals, improving the energy resolution
If the barrel were taken apart, the shaping time constants could be re-optimized
Were both the barrel and forward endcap to be rebuilt, a geometry with no real barrel/endcap break (à la H1) could be built without precluding access to the tracker
David Hitlin Frascati SuperB Workshop March 17, 2006 19
Particle ID The DIRC water standoff box is a source of background from
beam-related particles In a detector for the storage ring design it is desirable to remove
the SOB Doing so depends on development of compact DIRC readout
It is difficult, but perhaps not impossible, for a barrel DIRC and a rear EMC endcap to coexist Even if a readout that works in a magnetic field is developed,
there would be a substantial amount of material in the barrel/rear endcap corner
Endcap PID A proximity-focussed Cherenkov ring imaging device with
aerogel radiator(s) appears to be a good choice Presents 10-20% X0
Requires ~ 30 cm of space
David Hitlin Frascati SuperB Workshop March 17, 2006 20
PID geometry interacts strongly with the EMC
The current BABAR DIRC readout precludes a useful backward EMC endcap
An evolved design, with a quartz standoff and pixel pmt readout in a magnetic field poses its own severe limitations on an upgraded EMC If the readout is brought out beyond the barrel EMC, there
is perforce an awkward break between the barrel and BEC If the readout is inside the EMC, the barrel/EMC break can
be much more graceful, but there will be a rather large concentration of high Z material in the EMC corner region
David Hitlin Frascati SuperB Workshop March 17, 2006 21
SVT/Main tracking upgrade options
SVT Option Pros Cons/QuestionsVery small radius uncooled beampipeTwo layers of pixelsFive layer SVT
Most robust pattern recognition Best vertex resolution Allows lowest energy asymmetry
Most expensive Are pixels really needed?
Small radius cooled beampipeFive layer SVT
Less uncertain (at least until IP is designed and backgrounds calculated)
Vertex resolution is worse Energy asymmetry greater
In all options: remove support tube
Tracker Option Pros Cons/QuestionsDrift chamber Best momentum resolution Most expensive
Are pixels really needed?
Silicon strips Best rate capability Better solid angle coverage Less material in front of EC PID/EMC
Much more expensive Worse momentum resolution
David Hitlin Frascati SuperB Workshop March 17, 2006 22
EMC upgrade options
Option Pros ConsRetain Barrel & Forward Endcap (FEC)
[Add BEC]
Cheapest Radiation damage impairs performance Must disassemble to move Restricted solid angle [Awkward barrel/BEC interface]
Retain Barrel, new FEC
[Add BEC]
Second cheapest Improved FEC segmentation, resolution, speed
Radiation damage impairs barrel performance Must disassemble barrel to move [Awkward barrel/BEC interface]
Retain Barrel crystals, rebuild mechanics +New FEC and BEC
Allows better BEC geometry Can improve material, electronics Improved solid angle Improved FEC, BEC segmentation, resolution, speed
Radiation damage impairs barrel performance
New LSO EMC Better resolution, speed, segmentation More flexible geometry
Most expensive
David Hitlin Frascati SuperB Workshop March 17, 2006 23
PID/IFR upgrade options
PID Option Pros ConsBarrel - DIRC Proven concept
Good momentum range
Material in front of EMC Difficult to have backward EMC endcap
Endcap(s)
Proximity focussed Cherenkov
TOF
Extends PID solid angle
Extends PID solid angle
Material in front of EMC endcap(s) Compatible momentum resolution?
Material in front of EMC endcap(s)Extremely good timing in magnetic field required Compatible momentum resolution?
IFR Option Pros ConsBarrel LST Likely has adequate rate
capabilty and radiation hardness
Endcap LST May have adequate rate capabilty and radiation hardness
May require substantial additional shielding in upstream direction
David Hitlin Frascati SuperB Workshop March 17, 2006 24
Trigger/DAQ upgrade options
See talk by Gregory Dubois-Felsmann
David Hitlin Frascati SuperB Workshop March 17, 2006 25
Comparison – BABAR and Belle for SuperB
From Yamauchi’sHawaii 2005 talk
David Hitlin Frascati SuperB Workshop March 17, 2006 26
Comparison - II
From Yamauchi’sHawaii 2005 talk
David Hitlin Frascati SuperB Workshop March 17, 2006 27
Moving forward We need an R&D plan
Formulate R&D objectives Develop an R&D schedule Formulate a budget See David Leith’s talk
We need a reliable cost estimate of a BABAR (or Belle)-based upgrade
David Hitlin Frascati SuperB Workshop March 17, 2006 28
Conclusions The details of a SuperB detector depend intimately on
whether SuperB is a linear collider or a (new type of) storage ring
Parenthetic remark In 1977 I ran a group at Aspen that was charged with
designing (in the Summer Study sense) a detector for what eventually became the TevatronAt that time, it was undecided whether the machine would be based on collisions between the existing 200 GeV machine and a new 1 TeV superconducting ring, or whether the collisions would take place solely in the 1 TeV ring.In other words, would the CM be stationary in the lab, or moving in the lab (perhaps that’s where Oddone got the idea)The SuperB detector issue is trivial by comparison
BABAR, with very substantial upgrades, provides a suitable platform for a SuperB detector